The present invention relates to devices for the cutting of stacked sheet material and the like, and in particular to a cutting machine having an improved mounting arrangement for the knife holder to reduce stresses during cutting, and provide an improved cut.
Sheet cutters are generally well known, as disclosed in DE 44 40 754 C1. In current sheet cutters, the respective linear guideway has a guide rail, in which a guiding carriage is guided, on the side of the holding rack. A pin, which swivels and is located in a drilled hole in the knife holder, is connected with the guiding carriage. A radial needle bearing surrounds the pin. An axial bearing is provided between the knife holder and a nut screwed into the pin""s thread section; furthermore, an axial bearing is located between the guiding carriage and the knife holder. The large distance between the linear guideway""s mounting plane and the knife holder""s mounting plane in the pin is not advantageous for such cutters. As the mounting of the knife holder largely dictates the cutting level position of the knife held by the knife holder, the result is considerable distances between the cutting plane and the guide plane of the knife holder in the holding rack, whereby high bending moments are created as cutting is performed in the holding rack. In order to be able to withstand such high bending moments, the swivel bearing, as well as the linear guideway, must be closely dimensioned, which results in high construction and maintenance expenditures; further, considerable additional mass must be moved during the cut. Aside from this, the high bending moments created when cutting in the guiding carriage enclosing the guide rail cause the linear guideway to deform or widen. Imprecise guidance of the knife and cutting inaccuracy are the result.
Additional devices for the cutting of stacked sheet material having linear guideways mounted in roller bearing fashion for the knife holder are known from DE 42 06 338 A1 and DE 196 29 285 C1. A device for the cutting of stacked sheet material, which has a linear guideway mounted in a floating manner for the knife holder, is disclosed in GB 566 754.
It is the purpose of the present invention to obtain secure mounting of the knife holder in the holding rack, especially via the best possible mounting position of the knife holder, as well as the lowest possible bending moments, which are created by the knife""s position in the holding rack during the cutting process.
This problem with the aforementioned type of device is solved by equipping the knife holder with a bearing element in the area of each respective linear guideway, which swivels and is located in a drilled hole on the guiding carriage.
It is essential that the bearing element, which is specifically made as a bolt or pin, is mounted in the guiding carriage in a pivoting or swiveling manner. Thereby the power contact point of the bearing element can be positioned as closely as desired in reference to the cutting plane. The bearing element""s resulting power contact point is preferably selected in such a way that it coincides closely with the cutting plane. The result is a clearly directed, relatively small bending moment, which is transferred by the respective bearing element to the guiding carriage, during the cut. It is preferred that the position of the bearing element in the guiding carriage and the guiding carriage""s position in the respective guide rail be essentially on one plane or level. Cutting forces are therefore transferred without significant bending moments from the knife and/or knife holder to the guiding carriage via the respective bearing element and from there into the respective guide rail. Based on the invention""s design and arrangement of the aforementioned components, no distortion or widening of the bearing area is created, and no undefined clearance of the parts moving relatively towards each other can be found.
The guiding carriage""s guided bearing can be achieved in different ways. There is, for example, the possibility of providing only one guide rail, into which the guiding carriage is mounted as an exact fit. It is also conceivable to provide two guide rails in the area of the respective linear guideway, which form a pair of guide rails, between which the guiding carriage is located, and in which it is guided. The pair of guide rails may form a unit and hence exhibit an essentially U-shaped cross section, whereby the guide rails are integrated into two shanks, and the unit is connected with the holding rack in the area of the web linking the two shanks.
For a useful design development of the invention, it is provided that the bearing element be securely or tightly connected with the knife holder. This secure connection may, for example, be achieved in that the bearing element, preferably using a bolt screwed into the knife holder.
According to a preferred design development, it is provided that the mounting of the bearing element be mounted in the guiding carriage in roller bearing fashion. This may be done by using axial and radial bearings, especially a needle bearing, in order to keep with a minimum profile or construction area for the bearing. The bearing element""s axial and radial mounting in the guiding carriage, for example, is achieved with two separate pivot bearings, which are inserted into the guiding carriage and braced by screwing the bolt into the knife beam.
??According to this specific design, it is provided that the shorter guiding carriage located in the long guide rail, respectively?? the long guide rails have a relatively long length. It should correspond to at least half the length of the respective guide rail. It is therefore ensured that the guiding carriage can be guided in the guide rail, respectively guide rails, without tilting.
It is considered especially advantageous if the respective guide rail has an essentially M- or V-shaped cross section, and the guiding carriage""s section facing the respective guide rail exhibits an essentially V-shaped cross section. Due to the co-actions of the respective cross sections, it is ensured that the guiding carriage is precisely guided in the respective guide rail on cutting line plane, respectively the plane running parallel to it, as well as vertically to this plane.
The guiding carriage""s roller bearing in the guide rail, respectively the guide rails, may for example be done via a cage guided between them. With the co-actions of the M-shaped and V-shaped guide cross sections, the cage""s cross section is preferably designed in V-shape. It may be designed as an angular flat cage, which takes a number of rolling elements. It is entirely conceivable to provide a rotary guide of rolling elements, especially a rotary roller guide, instead of a guide using a cage.
In order to be able to precisely align the knife holder with the bearing, respectively the holding rack, an eccentric tappet to adjust the bearing element relative to the knife holder should be provided at least in the area of one of the two knife holder bearings.
The knife holder can be operated in different ways, for example in one-sided or two-sided fashion. With a power source acting on two sides of the knife holder, the knife holder and associated linear guideways may be dimensioned less closely, as no strong forces may be initiated by the knife holder. The respective power source may for example be a hydraulic cylinder or an electric motor drive using a crank drive.
The way the knife holder is mounted in the holding rack according to the invention in that the linear guideway""s symmetric plane (of the guiding carriage in the respective guide rail) and the rotary guide""s symmetric plane (of the bearing bolt in the guiding carriage) essentially coincide, whereby the cutting plane should also be in the area of this plane, respectively these planes, is of special advantage.
Additional characteristics of the invention are demonstrated in the attached claims, as well as in the figure descriptions and the figures themselves.